Twin propeller marine motor propulsion and steering unit



Sept. 25, 1951 J, sHlVELY 2,569,346

. TWIN PROPELLER MARINE MOTOR PROPULSION AND STEERING UNIT Filed July24, 1947 6 Sheets-Sheet l INVENTOR. JOHN J. SH/VELV A T TORNE V5 p 25,1951 .1. J. SHIVELY 2,569,346

TwIN PROPELLER MARINE MOTOR PROPULSION AND STEERING UNIT Filed July 24,1947 6 Sheets-Sheet 4 e2 44 45 z; 45 a; 77

1.93 m- /87 7/ 70 460 J 89 A4 A} 2 I49 76 40 I I66 I03 l a ms 69 m4 1 Ess 67 7 /5 F51 jo w \R [/4 "a /a/ 22 v 1/2 INVEN TOR. JOHN J. SH/l/ELY A7' TORNE Y5 J. J. SHIVELY 2,569,345 TWIN PROPELLER MARINE MOTORPROPULSION AND STEERING UNIT Filed July 24, 1947 e Sheets-Sheet 5 Sept.25, 1951 INVENTOR. JOHN J. SH/VELV A T TORNEKS Sept. 25, 1951 J J.sHlVELY 2,569,346

TWIN PROPELLER MARINE MOTOR PROPULSION AND STEERING UNIT Filed July 24,1947 6 Sheets-Sheet 6 4 9 I32 6? I85 m5 185 /99 A964 9 A??? I a a 3 K lI 5/ o 3 K 4, I I66 n \o 45 v I so 52 20 47 D 0 06 INVEN TOR. JOHN J.SH/VELV A T TORNE VS Patented Sept. 25, 1 951 TWIN'lRdFlELLER MARINEMOTOR PR6 PULSION AND STEERING UNIT J ohn J Shively, NevvYork," N.Application July 24,1947; Serial-No. 763,200

Steering unit.

An object of the invention is to provide an improved internal combustionengine for marine propulsion and the like,

;. Another object .is to provide an improved d of cooling andlubricating internal, combustion engines.

Another object is to provide an engine of the above type embodyingimproved cooling and lubricating means to carry out the method.

Another object is to provide an improved en-. gine and propellingcombination adapted to outboard mounting and operation.

A furtherobjectis to provide a device of the above nature embodying twinpropellersrotatable at equalspeeds from the common power'source; Afurther object is to provide a devicev of the.

above nature wherein steering:is,.accomplished by swinging thepropellersin relation to thepower source.

a A still further object is to, provide a device-of the above typewherein'the two vertical shafts transmitting torque to the propellersarerevolved in opposite directions whereby torque reaction is balancedto promote ease and uniformity in steering.

. A; still further object is to include common, means in 'a device ofthe above type to swing simultaneously the lines of thrust of bothpropellers outwardly and forwardly, whereby neu tral and reverseoperating positionsmay beprovidedwithout clutches or gear shifts andwherebythe two lines of thrust may be simultaneously shifted todiffering angular relation withv the boat by manipulation of thesteering means. 7

vAnother object is to provide propulsion and power means of the abovenature in which a common fluid may be used for lubrication thereof andfor cooling the internal combustion engine portion.

A yet further object is to rovide heat exchange means between the commoncooling and lubricating fluid and the Water in which the propel- JFigure 1 is a vertical sectional view of a pre' head and tubes;

; neutral and forward driving positiflns Rearwar'dly f dir 8 claims;(o1.115 1s) v e il gure L 1 i 2 is a. ert ca ir nsv s view .part allr.

in section approximately in the plane 2-2 Figure 1;

Figure? isanelevation of the unit viewed from the port lf a l W Figure 4is a horizontal sectional viewprinci p lly in he pl neeursp and1. ure 5is adetail illustration of thesteering ure 6 is ald as ammatic i lustior icf. the: propeilers Stra htfo wa d dr v pa s Figure 6a sa s mila ,sagramiil us r tine pare. allel swinging of the propellersin normalsteer.-

me; u 7 1 i i ar ag amr h wineethe;p ol-1 l rs swung outwa ds) neut alipit pn: Figure 7a illustrates one propeller directed .forward and oneaft; 7 ,1. Figure Bis a similar diagram v illustrating the; swinging ofthe propellers into straightreverse driving position; b r, Figure 9illustratesv apropeller setting between;

Figure 10 is aldetail frontsview ofthefpaneliboardand-associatedcontroller/erg ure 11 illustrates a .cmo ifica ionsinwhich steering and reverse controlare accomplishedzby the same leverorti'llerp n ,7 i

Figure 12 is 'a-rearview ofthe cylinder body-ror block with portions ofthe headrandrjacket .re.- moved; I

Figure 13 is a fragmentaldetail sectionrof an? alternate formpf; heat.exchanger andv I Figure 14-1is .a front elevationl of the same;Referring;;first to l jigures l 'and 2, the. numeral; generally.denotes; an engine .body, preferably, of cast aluminum or the like,which is bolted-2th a middle or drive shaft housings21., .Arclo'sureplate 22 is secure d to thefrontpfz bodyzm and; middle housing 2lBrackets ,23' andllg Figures 1 a a rmedi njth p a e;22-iand1.are hingedr wllv62 1 me nsqt a t ans ers e ulqe 25m a eiamii'memberie adapte d ftobe secu to h t ns m 1' hahp te hv mean r. $1 1M able e i se ews f f weand. o clams member 2.6, may be const slot 3!) a apped toj engagetransom 21% equalize drivingtstress o th t som duringoperation in revuse described. I' Ihe' bree s; .2 and videdflwitli 'bushiii J32 formacushionfmountingij i ctd eitnsions '33 on. clamp.

rubber or. the lile'to 3 member 26 have therein a series of cross-holes34 disposed on a common radius from the hingetube 26 as a center andadapted to receive a transverse thrust bolt 35. Abutments 36 on thelower housing 2| may be provided with resilient buffers 31 normallyengaging the thrust-bolt 35. A wide hook 38, secured on a rocker-shaft39 journalled transversely in the abutments 36, is adapted to be swungupward to engage the forward side of the thrust-bolt 35 by means whichwill be set forth hereafter in connection with the description ofreverse operation.

Four cylinder sleeves 48, 4|, 42 and 43 are disposed in the rear upperportion of the body 28, terminal flanges 44 on the sleeves beingrecessed in the rear body wall 45. The outer walls 46 of body 28 arespaced from the sleeves 48, etc. to form a jacket-space 46a. A head 41is secured to the body 28, forming a closure for the upper ends of thecylinder sleeves and having depressionsproviding combustion chambers 48.A suitable gasket 49 is interposed between the body 28 and the head 41.The usual spark plugs 58 are mounted in the head 41 in communicationwith the combustion chambers 48. The combustion chambers 48 extenddownwardly in L-head construction as illustrated in Figure 1, and areprovided with inclined inlet and exhaust valves 5I and 52, respectively.The valve stems 54 are guided in sleeves 55 and are fitted with suitableclosing springs 56. The inlet valves 5I communicate via cored passages51, Figure 12, through the body 28 and head 41 with an exterior manifold58 to which is attached a carburetor 59 of any suitable type, hereinillustrated as of down-draft construction. The exhaust valves 52 areconnected via downward passages 68 with a muiiier 6I secured to theunder side of the body 28.

Pistons 62 are slidably fitted in the cylinders 48, 4|, 42 and 43 andare provided with wrist pins 65 connected via connecting rods 66 withcrank-pins 61 of a transverse crankshaft 68, the latter being journalledin capped bearings 69, 69a, and 69b secured in the body'28. The shanks18 of the connecting rods 66 are preferably of U- shaped cross sectionto form troughs 1| adapted to catch lubricant and direct it via inclinedholes 12 and 13, Figure 4, to the bearing surfaces of wrist-pins 65 andcrank-pins 61.

A combined cam-shaft and jackshaft 14 is disposed in cap-bearing 15, 15aand 15b directly below the crankshaft 68.

The camshaft 14 is driven at one-half crankshaft speed via crankshaftpinion 16 and mating camshaft gear 11. While the pinion 18 and gear 11are illustrated as straight spur type, it will be understood that theymay be of helical or herring bone construction if desired. Exhaust cams18 and inlet cams 19 on the shaft 14 are provided to operate the valvesvia adjustable tappets 88 as illustrated in Figure 1.

The middle housing 21 comprises an upper portion forming a sump 8I,hollow vertical port and starboard columns or drive shaft housings 82and 83, and a hollow bridge 84 connecting the lower ends of the columns.The bridge 84 is shaped to act as an anti-cavitation plate to augmentpropeller efficiency, and also operates as a heat exchanger for theengine cooling system as hereinafter set forth.

" 'Vertical shaft tubes 85 and 86 are rotatably mounted in the columns82 and 83 respectively. Chain sprockets 81 and 88 are secured to theupper ends of the tubes 85 and 86, comprising parts of the steeringsystem as hereinafter described and also serving as thrust collars toretain the tubes against downward movement in the columns. Propellershaft housings 89 and 90 are rigidly secured to the lower ends of thetubes 85 and 86 respectively and may be provided with suitable skegs 89aand 98a. Horizontal propeller shafts 9| and 92, carrying propellers 93and 94 of opposite pitch respectively, are mounted in suitable bearings95 and 96 and are provided'with seals 91 to prevent leakage of lubricantfrom and entry of water into the housings 89 and 98.

Bevel gears 98 on the shaft 93 and 94 mesh with mating bevels 99 on thelower ends of vertical drive shafts I88 and H which are centrallydisposed in the tubes 85 and 86. Ball bearings I82, fitted in the lowerends of tubes 85 and 86 provide radial support at these points for thedrive shafts I88 and I8I and also take the vertical thrust of the bevelgears 99.

The upper ends of shafts I88 and IM are slid ably splined in upwardlydirected bevel gears I83 and I84, which gears are formed with lowersleeves H35 and I86 respectively, journalled in bushings I81 secured inthe upper ends of the tubes 85 and 86. Retaining collar I81a. may beprovided on the lower ends of the gear sleeves I85 and I86 to engage thelower ends of bushings I81.

The gears I83 and I84 are in mesh respectively with bevel gears W311 andI840, on the camshaft 14. It will be noted that gears W311 and l84a aresecured on the shaft 14 in opposed relation, meshing with gears I83 andI84 on diametrically opposite sides of the latter. By this arrangementit is evident that rotation of the camshaft 14 causes the verticalshafts I88 and I8I to be driven in opposite directions, oppositedirectional drive being imparted similarly through the previouslydescribed lower end gearing combinations to the two propellers 93 and94.

A hollow steering head I88 is journalled for horizontal rotation in theupper forward portion of the body 28 on the port side as shown inFigures 1 and 2. A steering handle or tiller I89, Figure 1, extendsforward from the head I88 and may be provided with a hinge joint I I8 topermit the hand grip portion III to be swung upward out of the way whendesired. An inner steering tube or pivot I I2, Figures 2, 4 and 5, isjournalled at the top in the upper end of the steering head I81 and atthe bottom in the middle housing 2I. An outer steering tube or sleeve H3is rotatably mounted on the inner tube H2. The lower end of the tube II3carries a sprocket II4 which is connected by a chain II5 with thesprocket 81 on the port shaft tube 85. Similarly, a sprocket H6 on thelower end of inner tube II 2 is connected by a chain II1 to the sprocket88 on the starboard drive shaft tube 89. An idler sprocket I I8 isprovided to allow the chain I I1 to clear the port tube 85 and its upperfittings. The idler II8 may be provided with eccentric mounting I I9 asindicated in Figure 6, to permit shifting it to tighten the chain I I1if necessary.

Opposed bevel pinions I28 and I2I, secured on the upper portions ofsteering tubes H2 and H3 respectively, mesh with a bevel gear I 22fastened to a pin I23 horizontally journalled in the steering head I88as shown in Figure 2. A forked reverse lever I24, Figures 1, 2, 3 and 5,is fastened to the pin I23 and is adapted to swing in a vertical plane,a second pin I25 being secured in the forked end ofthe lever andjournalled in the head I88 to insure lateral stability of the lever I24and gar l 22. -A 'spr ing-pressed latch 'l 26 i-n the liever 1 24 isadapted to selectively ehg'ai'ge-htches I2 1, I2 8- and 429' in quadrantBli-secured'to'the steering "head #8, and is --'adapted--to "bewithdrawn from the notches by-means of'a hand-grip lever I3I. I 1 g -Camlobes I32 on-the-under sides-oftheforked "portion of the reverse-leverI24 normally engage 'a' ring plate I33, which is horizontally hinged atWI, Figures 1 and-3. A r0dI3-5 links the hinged 'ring plate 133 with-asmallarm I3 6 entire-end "of the rocker shaft 39"which'-carries the'ho'o38 as previously noted. A compression spring -"on the rod I 35 issupported' by a small-fork secured to the front 'plate'2'2. "The sprin'gF31 urgesthe 'rod I'3'5'u'pward, tending to rockth'e farm "I 36 and thehook:3 8 upward. Inthenormal drforward position of thereverse"lever*I'Q'Qf the damlobes I32 hold the ring-plate I33 "andf'hence the hook 38in downward position, thehookthus g'o clearing the thrust boltr When"the reverse ifl'eve'r 12 i is swung upward out offorwardpos'if'tion'a's hereinafter more ful'ly'setforth, thel'obes I32withdraw from the ring plate I33;.al'lowing the spring I31 toro'ck "the"hook3'8 upward into 1 position to engage the forward side'of theb'olt35. IThus the unit islock'e'd against swinging ontward upon reversal ofpropelling'thrust. "Referring to Figure -2, it willbe se'en that'thesump '8I slopes'directly "into a pocket I39 surrounding the portdrive-shaft tube 85. Apertures I40 .in the tube 85 form passage-waysfrom 'the'sump pocket "I39 to the annular space MI in "the tube '85surrounding the drive shaft I60. '7 Lower apertures I il'lead via .allowerpocket 1112a to the hollow interior I43 of the 'br idge platetd.Upper .and lower pockets IM and "I45 are also provided around thestarboard drive shaft tube 1 86;.apertures 'I 36 and I l] leading'fromlthe pockets into the annular space IE8 around the drive shaft I6I. The lower pocket .l i5-opens into'the bridgeplate interior H53,whilethe upper pocket I14 is in communication with the cylinderjacke'tspace 16a via a cored passage I 49, Figures- 1,2 and .4.

Small helical impellers I158 and I=5I tare secured on the -drive shaftsIllfi andj QI-DQI near the lower -ends of th annular spaces MI .and I48respec- -tively, both impellers having thesamedirection of lead ortwist. A magneto I52 =is-m0untedon -an-upwald exv,tension I53 of thebody 20. The magneto is driven through an impulse couplin I5 4 0: knowntype -a'shaft I55, gears I56 and-I5'Iandza crank- "shaft pinion I58. Themagneto is connected with y the spark plugs by wires I52a inthesus-ualway, ,the wiring being cut away in the drawingsto simplify thelatter. The numeral il59 denote ta flywheel secured to one end-of the:crankshatt BB, Ia cover I 69 :beingsecured on the endofithe fly- ;wheelhousing I6I. A combined :oil filler-and .breather I62 in the upper rearportionof the housing IBI is surmounted'loy-acapHi3. -;-An -oil depthgage I64, normally "held in a-clip I-GSI' Fig- ;-ures 2 and 4, may beremoved for inspection f-through the breather 1.62 in the knownimannericommon ito automobile engine practice. The left if or port endofthelcrankshaft-fill carries a starter :---:of any suitable type,herein illustrated bya ropes heave I56 having :notches l6]forzreceivingthe end of a starting :rope. A seal .I68,-held in a:closure cap xlifigt,a=prevents outward .leakageof luabricantalong theshaft 168.

A fuel tank ":I'Ill, Figures :1- and.2,lis mounted :aonathe top ofthebodyfll, and isadapted to feed i ituelithrough aashut-soif valveI;'I;I v and wtuloe. 1. 12

to --the 'carburetor 59. the internal structure 0f f uel tanks is wellknown and .forms in itself no' part of the present invention, the tankIIfl is .not shownin section.

Choke and throttle control shafts I13 .and I14 extending forward belowthe tank. I Ill and through a :small 'panel or dashboard I15 on theforward side of the body 20, carry operating levers I16 and I'llrespectively. A turn-off switch US for the magneto I52 is also mountedon the panel I15. The fuel valve I'II may be controllable from the-frontof the unit through a rod I19 and a handle I80 in front of the panelI75, as shown in Figure 10. A removable lower shield 'I8-I-and-a hoodI82, Figures 1, 3 and 4, protect "the carburetor, spark plugs, magnetoand related parts from splash and rain. To clarify the showing of theinner parts, the hood and shield are removed in Figures 2 and 12.

Louvres I83 in the hood I82 provide for engine ventilation andforlintake air to the carburetor 59. In operation, the unit is clampedto the transom 21 of the boat 28 by means of the screws 29 andpreferably also by the lower bolt 3|, Figure-l. Before starting themotor, lubricant is poured into the unit through the filler [.62 untilafter filling all the described inter-connected lower spaces of theunit, the lubricant stands approximately at the level indicated by thedot and dash line I84, Figure 2. The tank I IB having been sup-pliedwith fuel and the latter admitted to the carburetor 559 .via the valveIll and tube I'I2, the magneto switch IE8 is turned on and the motorstarted by means aof the 'usual rope (not shown) applied to the notchedsheave I56 in a well-known manner.

Rotation of the crankshaft in the direction indicated-by an arrow .inFigure '1 .causes the propellers 93 and "95 'to be driven in .opposite.the upper pocket I'M and the cored passage I49 in to the cylinderjacket space 46a. The fluid circulates along and around thecylindersleeves,

"I86 of the cylinder head 41.

passage I 86a to the main or crankcase portion of the body 20.

"Collecting in the sump 8|, the fluid moves down through the annularspace I39 in the drive shafttube 85, thence through the interior I43 oftheplate 84, from which it is again forced upward through the shaft tube86 and the cored passage I49 back to the cylinder jacket. The impellerfI5Il,.having the same direction of twist a'sthe impeller I5I butrevolving in the opposite .directiomexertsa downward thrust on the fluidin the'tube'85pthus operating as a backing or Tbo os'ter pump to assistthe impeller I5I in mainltalin'ing circulation.

iFrom .the'above description, it will be evident that the lubricatingfluid in its passage through :the engine jackets acts as a primarycoolant for the en ine. the heat extracted from the latter {out-principally through the walls of the heat-- exchanging bridge plate'8 lto the water in which the plate is normally immersed. The impellers I59and II are so proportioned as ,to maintain an ample volume of fluidcirculation to provide proper cooling at all times. The heat-exchangerplate 84 may be constructed with interior flanges or ribs 8 1a, asillustrated in Figure 13, to direct the flow of fluid and increase theinterior heat exchange surface between the fluid and the walls of theplate. Longitudinal exterior ribs 84b, Figures 13 and 14, may bedisposed on the, outer surfaces to increase the heat-exchange areabetween the plate and the surrounding water if desired on larger orheavy-duty units.

As previously stated, the circulating cooling fiuid is also a lubricant.It is therefore evident that lubrication for various bearing surfacesmay be provided by tapping into the cooling system at suitablelocations.

Referring to Figure 4, the numerals I81 and I98 and I89 denote oilpassages from the jacket 159a to the main crank-shaft bearings 69, 69a

and 691) respectively. Similarly, passages such as I9I, Figure 1, leadfrom the laterally extending lower portion I92 of the jacket 56a to thevarious camshaft bearings. The tappet-plungers 89, Figure 1, extendthrough the lower jacket portion I92 and receive lubrication therefromdirectly.

Oil-holes I93, Figures 1 and 4, are disposed in the cylinder sleevesdirectly above the troughs II in the connecting rods 66. Lubricant fromthe jacket 46a feeds through the holes I93 to lubricate the uppersurfaces of the pistons, and a certain amount drops into the connectingrod troughs 'I'I while the pistons are on the upper portions of theirstrokes. From the troughs, lubricant passes through the holes I2 and I3to lubricate the wrist-pins and crank-pins. To ensure ample feed to thetroughs IT at high speed, small spouts I94 may be disposed asillustrated in Figures 1 and 2 so as to clear the lower ends of thepistons at the bottom of their strokes. Oil from the rapidly movingconnecting rods and crankshaft is splashed throughout the cylinders andinto the interior of the pistons, furnishing lubrication throughout thecylinder walls and also cooling the piston heads. It is further evidentthat lubricant is thrown about or splashed throughout the entireinterior to the body 29, and this splash, together with the fluidreturning from the jacket via the passages I86a, lubricates the gearing,cams, chains and other working parts previously described. At pointswhere it is desired to apply a continuous flow of cool lubricantdirectly to working surfaces, as for example the bevel gear combinationsI03'-I 03a and" I94I04a, spouts I95, Figure 2, may be connected into thelower jacket portion I92. Small apertures I96, Figure 1, directlubricant from the jacket ite on the exhaust valve stems 54 thuslubricating and cooling the stems and springs."--

This lubricant is caught by a closure plate I91 and returned to theinterior of body through holes I98.

A tube I99, Figures 2 and 12, leads from the top of the jacket 46a to apocket 200 about the:

magneto drive shaft I55. This tube furnishes lubricant to the shaft I55and also operates as a vent to prevent possible air or vapor lock in thejacket 46a. It will be understood that the jacket outlet openings I 86a,Figure 12, are sufiiciently constricted as to maintain flow through thetube I99 and the other described lubrication passage under all normaloperating conditions, due to the ample pumping capacity of the im:pellers I50 and NH. 7

By means of the oil cooling system described, the invention avoids thetroubles incident to (iirect water cooling such as scale deposits,internal corrosion, possible freezing of water in the jackets, etc. Itthus accomplishes the advan-- tages of uniform liquid cooling but avoidsthe complications inherent in the use of a. second circulating fluid inaddition to the lubricant and which must be kept separated from thelatter. In addition to the ease and simplicity with which lubrication issecured by tapping into the cooling system as already described, theinvention permits the use of thin iron or steel cylinder sleeves in thealuminum body orblock 20 without the necessity for press fits with thelatters attendant high cost and difficulties from differences in thermalexpansion, since the flanges 44 are clamped by the head 41 and gasket49, while any seepage of oil along the sleeves into the crankcase isimmaterial. Cylinder heat is transmitted through the thin uniformsleeves directly to the coolant, without the necessity of passingthrough a joint and a second wall of metal, as occurs in the usualengines having wearing sleeves inserted in cylinders forming part of themain block.

In the preferred form of the device as illustrated herein, the lowerbevel gear combinations 98-99 are lubricated by special gear-grease,filler plugs 2IlI being provided in the housings 89 and 90. Seals 292around the vertical shafts I" and IOI keep the lower gearing lubricantseparated from the circulating lubricant in the tubes and 8B. In case insome embodiments it is desired to lubricate the lower bevel gearcombinations with the same lubricants as that used in the circulatingsystem, the seals 292 may be omitted. To prevent leakage of oil outwardor water inward along the outside of the tubes 85 and 86, seals 205 aredisposed around the tubes as shown in Figures 1 and 2.

The operation of the steering and forward or rear drive control is asfollows:

With the reverse lever I24 in the position shown in Figures 1, 3 and 5,both propellers are directed straight astern as illustrateddiagrammatically in Figure 6, the boat consequently being drivenstraight ahead. When it is desired to turn, the tiller I99 is swung inthe usual manner. The lever I24 being held by the latch I26 in thequadrant notch I2'I, the gear I 22 and pinions I20 and I2I are locked,so that the entire steering head and the tubes H2 and H3 turn as a unit.The turning motion is transmitted equally via the sprockets H4 and IIii, the chains H5 and III, sprockets 81 and 88, and shaft tubes 85 and86 to the propeller shaft housings 89 and 90, causing the propellers 99and 94 to be swivelled at equal angles in parallel relation asillustrated in Figure 6a. Thus steering to either side is accomplishedat any angle governed by the swing of the tiller, the thrust directionsof the two propellers remaining parallel throughout.

When it is desired to drive the boat in reverse or to stop forwardmotion, the lever I24 is thrown upward through 90 degrees until thelatch I26 engages the upper notch I29, Figures 1, 3 and 5. In theembodiment illustrated in Figures 1, 2, 3 and 5, the steering head gearI22 has double the pitch diameters of its meshing pinions I20 and I2I.Consequently, the rotation of the gear I22 through 90 degrees rotatesthe pinions through degrees in opposite directions, and these motionsare transmitted through the previously described sprocket and chainmechanisms, causing the propellers 93 and 94 to be swivelled outward andforward through 1 80 degrees to .the .direct reverse driving positionillustrated in Figure 8. Obviously, the boat may be steered in reverseby swinging the tiller as usual, the engagement of the latch I 2 6 innotch I29 holding the steering head gear locked and causing thepropellers to be swivelled in parallel in the same manner as describedfor forward driving position.

Figure 7 illustrates .a neutral position, in which the reverse lever I24is swung to an intermediate position, the latch 'IZ-I occupying thenotch I28 and the tiller I09 being in central position. In thisposition, bothpropellers are turned laterally outward and while they maycontinue to revolve, their thrusts are directed outward in oppositedirections and consequently transmit no motion'to the boat.

Should it be desired to turn in very short space, the propellers may beplaced in neutral position as described and the tiller I09 is thrownhard over to either side desired, as illustrated in Figure 7a. Thisoperation directs one propeller torward and the other astern, giving thesame powerful turning efiect as that achieved by reversing one engine ofa twin-screw vessel.

Obviously any desired number of relative angular propeller settingsintermediate those described may be secured, for which any numberofcorresponding notches such as IZ'Ia and I28a, Figure 5, may beprovided in the quadrant I30. Figure 9 illustrates an intermediatepropeller position between forward and neutral, as when the latch I26 isengaged in notch I2'Ia. This setting causes only a component of thepropeller thrusts to be transmitted to the boat, in case, for example,where it is desired to move at speed below the normal lowest speedattainable with throttled engine and parallel propeller drive. A swingof the tiller can be utilized to direct one propeller astern and theother outboard to any degree within the range of the tiller.

.It is obvious that any other desired combination of reverse leverposition and tiller operation can be effected to facilitate maneuveringand speed control.

In the embodiment of the invention already described, the tiller I09.and reverse lever I24 are separate members. Figure II illustrates amodification in which a single lever 203 is utilized .both for steeringand reverse control. To provide proper steering leverage in reverseposition, the ratio of the pitch diameter of the steering head gear IZZais made larger in proportionto that of the pinions IZiia and I2Ia, thusdecreasing the upward angular arc of the lever 203 along the lockingsegment 204 necessary to throw the device into reverse position.Additional reversing leverage to compensate for the, decreased angularmovement may be secured by increased L length of the lever 203. Inaddition to operationof the device with the reverse lever latched toanyone of the notches, the operator may also hold the lever unlatched inany intermediate position and shift it back and forth at will, givingahigh degree of maneuverability.

From the foregoing description it is evident that the device providesthe effect of an infinite speed ratio between the engine and the boat,

from full speed ahead through neutral to full,

astern, without the use of change gears, clutches, feathering-bladepropellers or the like. It is well known that the reversal of a boat byswinging a single propeller through 180 degrees as in some prioroutboard practice presents dimcu equally easy in either direction.

and some hazard, especially if attempted in emergency at high speed andwith a powerful motor, since the lateral thrust during the swing tendsto throw theboat stern around. With the present invention the lateralthrusts of the two propellers remain in balanceduring their swings,eliminating the above difiiculties. Obviously the device, whilecontaining no clutch or feathering blade propeller, .allows the engineto be started and warmed up-before starting the boat,-andsimilarly theboat may be stopped without stopping the engine.

A-lthough'in idling or neutral position no "drive is communicated to theboat, the propellers still revolve in the water, reducing tendency tothe injurious racing of the motor common to'drives employing releasingclutches. Bythe combined operation of the reversin lever and tiller, aspre-. viously' noted, the unit achieves the maneuvering advantages of atwin engine drive but with a single engine and means of .control.

With dynamic steering by means of a single propeller driven by a singlevertical shaft, .as in prior outboard practice, the vertical driveresults in torque in one-direction which reactson the steering means.UIn-thecase of motors wherein only the lower unit .is turned insteering-the unidirectional torque is thedirect result of pro.- pellerresistance onthe lower level gear combination, while in motors in whichthe entire plant including the power head is turned, the torque is theresultant of unbalance between torque reaction and torque vibration. Ineither case the unidirectional. force makes steering harder in onedirection than the other, and re;- quires the-use of various lockingdevices to assist in holding a course .and to prevent the propeller fromkicking or walking? around if the tiller is released. In the presentinvention, wherein the two vertical drives operate in oppositedirections, the torque reactions automatically neutralize each other inthe locked steering head, so that steering is substantially balanced andIt is obvious that this elimination of torque resistance tosteeringishigh-lyadvantageous both in point of comfort-andsafety, especially inthe case of comparatively powerful motors. The structure of the presentinvention, in addition to providing balanced steering asset forth, alsorelieves the boat of the effects of unbalanced torque reaction about thepropeller shaft axes. In single propeller craft this torque reactioncauses a tendency tO listing or canting of. the hull to one side throughvarious degrees, dependent on the proportion of propeller torque to hulldimensions, and is so seriousa factor in high powered craft as to causedanger of capsizing if a turn is made at high speed in a directionwherein centrifugal force acts in the same direction as the torque list.Furthermore, thevariations in .hull list necessary to resist propellertorque, which variationsarise H 11 entirely within the rigid structureof the propelling unit itself, thus automatically giving the advantagesof twin screw stability while permitting the application of high powerto hulls of any desired type including, for example, very lightoutboard. racing types.

While the invention has been described in preferred form, it is notlimited to the exact embodiments illustrated, as various changes andmodifications may be made without departing from the scope of theappended claims.

What is claimed is:

, 1. In an outboard propulsion unit, in combination, an engine, twosubstantially horizontal propeller shafts, propellrson said shafts,vertical driving means operatively connecting said engine and saidshafts, steering means including a swinging head to swivel said shaftsand said propellers, said vertical driving means being operable by saidengine to exert torques on said steering means in opposite directions,whereby torque resistance to operation of said steering means may beeliminated, and manual means operable through said head to vary therelative axial orientation of said shafts.

.2. In an outboard propelling unit, in combination, a casing, aninternal combustion engine in the top of said casing and having atransverse main shaft, a pair of hollow columns on the bottom of saidcasing, two vertical tubes rotatably" mounted in said respectivecolumns, vertical drive shafts rotatably disposed in said tubes,housings secured to the lower ends of said tubes, propeller shaftsjournalled in said housings, propellers secured to outboard ends of saidpropeller shafts, gears connecting said vertical shafts to saidpropeller shafts, gear means connecting said main shaft to said verticalshafts to drive said vertical shafts, a vertical steering pivotjournalled in said housing, a steering sleeve rotatably mounted on saidpivot, a sprocket on said steering pivot, a second sprocket on one ofsaid shaft tubes, a chain connecting said sprockets, a second chain andengaged sprockets operatively connecting said steering sleeve and saidother shaft tube, a steering head on the top of said pivot and saidsleeve, oppositely directed bevel pinions secured respectively to saidpivot and said sleeve in said head, a bevel gear engaging said opposedpinions, means to turn said bevel gear to rotate said pinions inopposite directions and thereby change the relative angular positions ofsaid pivot and said sleeve, and means to lock said gear turning meanswhereby said steering head, sleeve and pivot may be swivelled as a unit.

3. The combination claimed in claim 2 wherein said bevel gear turningmeans comprises a lever pivotally mounted on said steering head andoperatively connected to said bevel gear, and wherein said locking meanscomprises a latch in said lever and a sector secured to said head andhaving notches adapted to be engaged by said latch.

4. The combination claimed in claim 2 wherein said bevel gear turningmeans comprises a single lever pivoted to said steering head andoperatively connected to said bevel gear, said lever being movable inone plane to move said bevel gear in said headand in another plane toswivel said head, steering pivot and steering tube as a unit.

5. In an outboard propulsion device, in combination, an engine, twinpropellers, driving means operatively connecting said engine to said twopropellers to simultaneously drive the same, common means including asteering lever to swing both said propellers substantially in the planeof their axes in predetermined relative angularaxial relationship, andmeans to alter: said predetermined relative angular axial rela-'tionship.

6. man outboard propulsion device, in com-- bination, an engine, twinpropellers, driving means operatively connecting said engine to said"two propellers to simultaneously drive the same,- common means includinga member movable in one plane to swing both'said propellers in the planeof their axes in predetermined relative angular axial relationship andmovable inan other plane to alter said predetermined relative-"- angularaxial relationship.

7. In apropulsion unit for use on a marinecraft, in combination, anengine having a main? shaft disposed transversely of said craft, twinpropellers of opposite pitch direction, common means selectivelyoperable to swing both said propellers to steer said craft and to changethe relative axial orientation of said propellers, and driving meansconnecting said engine to said propellers and adapted to drive saidpropellers in opposite torque directions whereby torque resistance tooperation of said steering means is equalized, said driving meansincluding two vertical shafts, gearing means connecting said verticalshafts to said transverse shaft to drive said vertical shafts inopposite directions, and gears connecting said vertical shafts to saidpropellers.

8. In a propulsion device adapted to be at.- tached to a boat, incombination, two propellers having shafts, means to drive said shaftsand propellers, common steering means selectively operable to normallyretain said shafts in forward driving position relative to said boat andto swing said shafts and propellers substantially in the plane of theiraxes outwardly and forwardly in opposite angular directions into re--verse driving position relative to said boat, and

means on said common means to mechanically latch said shafts in saidreverse driving position and in predetermined angular positionsintermediate said'forward driving position and said reverse drivingposition, said propellers in one of said intermediate positions beingdirected in opposite outward thrust relation whereby said boat mayremain stationary while said propellers revolve.

JOHN J SHIVELY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

